"The airtight "hot suite" in the laboratory of the final suspect in the 2001 anthrax mailings lacked systems capable of freeze-drying fluid anthrax samples into dry spores of the type used in the attacks, the U.S. Justice Department said in court documents filed on Friday (see GSN, May 20).

While the department reaffirmed its stance that deceased U.S. Army microbiologist Bruce Ivins was "more likely than not" the perpetrator of the mailings that killed five people, it did not suggest how he might have produced the dried anthrax, several news organizations said on Tuesday in a collaborative report published by ProPublica. The Florida court filings specify that the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick, Md., had not placed "the specialized equipment" in the suspect's restricted work area "that would be required to prepare the dried spore preparations that were used in the letters."

The department's acknowledgment heightens doubts about its findings against Ivins, who killed himself in July 2008 before facing any charges, according to the news report. The government declared in early 2010 that it had wrapped up the anthrax investigation and named the scientist as the sole perpetrator in the attacks. No direct evidence was ever found to connect the researcher to the crime, however, and a $100 million probe conducted over eight years failed to demonstrate beyond doubt he sent the anthrax and to determine another means by which he could have prepared the material."